Gelatin Causing Diacetyl

[Almighty]

The diacetyl has happened in my latest 3 batches (1 with S-04 and 2 with WLP028 Scottish Ale yeast) and I can't figure out why. The only thing that I have changed from my normal process is adding gelatin in the keg.

This first happened in my Best Bitter which was fermented at 65-68 and done in about 4 days. Then held around 70 for another week. I entered this beer in the Club Only Competition and it scored in the mid 30s. But about a week and half later in the keg it turned into a diacetyl bomb. The same thing happened to my Scottish 60/- that I let ferment out for 2 weeks. And now it seems to have happened in an IPA.

I am decently sensitive to diacetyl and I did not taste any in the IPA when it was first tapped. I still have a half of keg of the IPA at home that didn't get any gelatin and I cannot detect any diacetyl.

At first I thought it was a pedio infection. After each of these batches I tore apart my kegs and replaced all my draft and transfer lines. Also the problem is kicking in about 1 or 2 weeks after kegging and is cold the entire time. Plus there is no other off flavor or hint of sourness. I just can't imagine the pedio working this quickly in these conditions.

This problem has been driving me crazy.

 

[Walker]

The diacetyl has happened in my latest 3 batches (1 with S-04 and 2 with WLP028 Scottish Ale yeast) and I can't figure out why. The only thing that I have changed from my normal process is adding gelatin in the keg.

This first happened in my Best Bitter which was fermented at 65-68 and done in about 4 days. Then held around 70 for another week. I entered this beer in the Club Only Competition and it scored in the mid 30s. But about a week and half later in the keg it turned into a diacetyl bomb. The same thing happened to my Scottish 60/- that I let ferment out for 2 weeks. And now it seems to have happened in an IPA.

I am decently sensitive to diacetyl and I did not taste any in the IPA when it was first tapped. I still have a half of keg of the IPA at home that didn't get any gelatin and I cannot detect any diacetyl.

At first I thought it was a pedio infection. After each of these batches I tore apart my kegs and replaced all my draft and transfer lines. Also the problem is kicking in about 1 or 2 weeks after kegging and is cold the entire time. Plus there is no other off flavor or hint of sourness. I just can't imagine the pedio working this quickly in these conditions.

This problem has been driving me crazy.

Something isn't making sense here.

Diacetyl is produced by the yeast early in the fermentation process. By the time the beer is done fermenting, your beer will contain all of the diacetyl that it is ever going to contain.

It doesn't make sense that you are having diacetyl suddenly appear after fermentation is done.

 

[boo boo]

Unless it is in the taps itself. I had a buddy have it in the taps and as soon as he cleaned them it went away.

 

[twigboy2000]

Likely diacetyl precursors were in the beer at the time of kegging. If the kegs weren't purged the O2 could have reacted with the precursors to result in diacetyl.

You can test it like this: http://www.winning-homebrew.com/diacetyl-test.html to help determine if the beer is ready to come off the yeast (in regards to diacetyl).

My opinion, just leave it in the primary for 3 weeks. Why rush?

-chuck

 

[Almighty]

You can develop diacetyl after fermentation, this paper by White Labs is pretty good.
http://www.whitelabs.com/beer/Diacetyl_Time_Line.pdf

I have replaced the draft lines (gas and liquid) and the problem still occurred but only with kegs that received gelatin.I had 2 side by side kegs of IPA and one has diacetyl and one doesn't. The one with gelatin developed a diacetyl problem after a week.

I figured 2 weeks was plenty for beers that were done with active fermentation in 4 days.

My thoughts:
1. The Knox gelatin must be reacting with the diacetyl precursors - Strange because many others have had great results
2. The beer is truly not done and the gelatin is taking the yeast out of solution too soon.

Here is my procedure, let me know if you see any problems:
http://jeffreycrane.blogspot.com/2011/02/homebrew-notes-using-gelatin.html

 

[Gremlyn]

Hey, I remember drinking one of those beers! I highly doubt that gelatine is reacting chemically with acetolactate in your beer, but something odd is up. I've used gelatine plenty of times and never had an increase in diacetyl. How long are you cold crashing the kegs before adding the gelatine? Are you drawing off the settled out yeast cake prior to adding the gelatine? I found an article, which I couldn't access the full PDF of, but it did suggest that upon adding gelatine to beer and stirring can increase diacetyl in solution. The article is here: http://pubs.acs.org/doi/abs/10.1021/jf970994l

When I've added gelatine in the past I've not shaken or stirred the keg, just poured it in and let it sit a while. There is possibly something to that?

 

[Gremlyn]

OK, I got a copy of the article. I misread the abstract in my haste and it wasn't about beer at all, but release and sensory perception of diacetyl as a flavour. It's not entirely relevant to this topic, but the take away from reading it is that gelatine binds to diacetyl, so adding gelatine to your beer should not cause a release of diacetyl to occur, in fact it should be the opposite.

 

[Almighty]

Hey man, yeah it happened again.
I try to add the gelatin at the same time I rack. It is just easier to only open the keg one time. After I add the gelatin, then I purge the head space a few times and then swirl.

I forgot to add above that I did try to do a diacetyl test on the 60/-. Where I heated it up to 140 for 15- 20 minutes. I could not get any diacetyl from that sample, but that sample I tried it with was in a different keg that I didn't use gelatin on and had been sitting at 70 for an additional 2 weeks.

My latest batch I will do a diacetyl test before I rack to the kegs. And this batch is still with the WLP028 Scottish yeast.

 

[Gremlyn]

So you don't add the gelatine to cold beer then? I always let my beer sit a few days to cold crash, pull off a pint to get the settled out yeast, and then add the gelatine. Not sure if any of that matters, but my reading led me to believe that it's better to add gelatine to cold beer than warm beer.

 

[Almighty]

Now, that I think of it. I have done it both ways.
The first time with the Best Bitter I added gelatin a week later after it was carbed.
And the last 2 times it has been at racking

 

[spiny_norman]

I've had great success with gelatin, but I use it in the primary. After 3 or 4 weeks (I usually dry hop), I cold crash to 34 then add the gelatin. After 2 or 3 days it's dropped clear and then I transfer to the keg. That way the gelatin is only in contact with the beer for a short period of time.

(I transfer from the fermenter to the keg with a CO2 push so the sediment does not get disturbed).

 

[HiGravShawn]

2. The beer is truly not done and the gelatin is taking the yeast out of solution too soon.

This would get my vote. I have never had any such problems with gelatin and I use it almost every beer style lighter than a porter. I always let fermentation go at least 17 days total before cold crashing and adding gelatin for three days to hit my usual 21 day ferment.